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RFC 1813 - 6. Appendix II: Lock manager protocol

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### 6. Appendix II: Lock manager protocol

Because the NFS version 2 protocol as well as the NFS version 3 protocol is stateless, an additional Network Lock Manager (NLM) protocol is required to support locking of NFS-mounted files. The NLM version 3 protocol, which is used with the NFS version 2 protocol, is documented in [X/OpenNFS].

Some of the changes in the NFS version 3 protocol require a new version of the NLM protocol. This new protocol is the NLM version 4 protocol. The following table summarizes the correspondence between versions of the NFS protocol and NLM protocol.

           NFS and NLM protocol compatibility

                   +---------+---------+
                   |   NFS   |   NLM   |
                   | Version | Version |
                   +===================+
                   |    2    |   1,3   |
                   +---------+---------+
                   |    3    |    4    |
                   +---------+---------+

This appendix only discusses the differences between the NLM version 3 protocol and the NLM version 4 protocol. As in the NFS version 3 protocol, almost all the names in the NLM version 4 protocol have been changed to include a version number. This appendix does not discuss changes that consist solely of a name change.

6.1 RPC Information

6.1.1 Authentication
6.1.2 Constants
6.1.3 Transport Address
6.1.4 Basic Data Types

6.2 NLM Procedures

6.2.0 Procedure 0: NULL - Do nothing

6.3 Implementation issues

6.3.1 64-bit offsets and lengths
6.3.2 File handles

Next: 6.1 RPC Information

Connected: An Internet Encyclopedia
RFC 1813 - 6. Appendix II: Lock manager protocol